- #1

aJaguarinRed

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## Homework Statement

A 1.2 g pebble is lodged in the tread of a 0.76-m automobile tire, held in place by static friction that can be at most 3.6 N. The car starts from rest and gradually accelerates on a straight road. How fast is the car moving when the pebble flies out of the tire tread?

## Homework Equations

I looked at the Chapter references and found v=ωR or v=2∏R/T where T=the period of the circle.

**3.Attempts**

1.I thought of Torque of the wheel but I can't find the Inertia (mass of tire not given) and I have no idea what the magnitude of the force rolling the tire.

2.I tried a=F/m and got a=3.6N/.0012kg=3000 m/s

^{2}.

3.I thought of the torque as a result of the static friction and computed τ=3.6N*0.38m=1.368N*m but how do I apply that to find the velocity of the car? I can't use τ=Iα because while I have the mass of the pebble I don't have the mass of the tire and if I used the pebble I don't know the radius of the pebble (if there is one). So this method won't work.

4.V=2∏R/T is useless because the problem does not give me time at all. And I would need time to find the period and/or velocity.

My largest obstacle so far in this course is my trouble in decomposing the components. Would anyone mind helping me get started in solving this problem?

Thanks